Number of stars brighter than visual magnitude n-1.

Terms

a(0) =1a(1) =4a(2) =15a(3) =49a(4) =172a(5) =511a(6) =1600a(7) =4968a(8) =15328a(9) =40858a(10) =82484a(11) =106963a(12) =114376a(13) =116592a(14) =117100a(15) =117127a(16) =117128a(17) =117129